scholarly journals Soil Carbon and CO2 Efflux as Influenced by the Thinning of Loblolly Pine (Pinus taeda L.) Plantations on the Piedmont of Virginia

2008 ◽  
Vol 54 (1) ◽  
pp. 58-66 ◽  
Author(s):  
Marcus F. Selig ◽  
John R. Seiler ◽  
Michael C. Tyree
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Loblolly Pine ◽  
Mineral Soil ◽  
Significant Variable ◽  
Co2 Efflux ◽  
Soil Fraction ◽  
Fine Soil ◽  
Pinus Taeda L ◽  
And Storage

Abstract The thinning of loblolly pine plantations has a great potential to influence the fluxes and storage of carbon within managed stands. In this study we investigated the effects of thinning on mineral soil carbon distribution and storage 14 years after the thinning of an 8-year-old loblolly pine plantation on the Piedmont of Virginia. Additionally, we examined patterns of soil CO2 efflux (Es) for 1 year after the second thinning of the same stands at age 22. The study was conducted using three replicate 0.22-ha stands planted using 3.05 × 3.05 m spacing in 1980. Soil carbon in the fine soil fraction (<2 mm) was evenly dispersed throughout thinned plots, and random sampling techniques were adequate for capturing spatial variability. Soil carbon decreased with depth, was higher at all depths in thinned stands, and was significantly higher (P = 0.06) at the 10- to 20-cm depth in the thinned stands (1.04%) compared with unthinned stands (0.76%). Soil temperature was approximately 1–2°C warmer in the growing season and 1°C cooler in the dormant season in thinned stands. Soil moisture was consistently higher in thinned stands by approximately 5%. Temperature was positively and significantly correlated with Es in thinned and unthinned stands. When modeled using regression, thinning was a significant variable for predicting Es (P < 0.0009) but explained less than 1% of the variation. Whereas thinning decreased Es when standardized to a constant temperature, actual Es was elevated in thinned stands because of higher soil temperature.

scholarly journals Variability of above-ground litter inputs alters soil physicochemical and biological processes: a meta-analysis of litterfall-manipulation experiments

2013 ◽  
Vol 10 (11) ◽  
pp. 7423-7433 ◽  
Author(s):  
S. Xu ◽  
L. L. Liu ◽  
E. J. Sayer
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Meta Analysis ◽  
Mineral Soil ◽  
Biogeochemical Cycling ◽  
Litter Addition ◽  
Litter Removal ◽  
Litter Manipulation ◽  
Below Ground ◽  
Soil Temperature And Moisture

Abstract. Global change has been shown to alter the amount of above-ground litter inputs to soil greatly, which could cause substantial cascading effects on below-ground biogeochemical cycling. Despite extensive study, there is uncertainty about how changes in above-ground litter inputs affect soil carbon and nutrient turnover and transformation. Here, we conducted a meta-analysis on 70 litter-manipulation experiments in order to assess how changes in above-ground litter inputs alter soil physicochemical properties, carbon dynamics and nutrient cycles. Our results demonstrated that litter removal decreased soil respiration by 34%, microbial biomass carbon in the mineral soil by 39% and total carbon in the mineral soil by 10%, whereas litter addition increased them by 31, 26 and 10%, respectively. This suggests that greater litter inputs increase the soil carbon sink despite higher rates of carbon release and transformation. Total nitrogen and extractable inorganic nitrogen in the mineral soil decreased by 17 and 30%, respectively, under litter removal, but were not altered by litter addition. Overall, litter manipulation had a significant impact upon soil temperature and moisture, but not soil pH; litter inputs were more crucial in buffering soil temperature and moisture fluctuations in grassland than in forest. Compared to other ecosystems, tropical and subtropical forests were more sensitive to variation in litter inputs, as altered litter inputs affected the turnover and accumulation of soil carbon and nutrients more substantially over a shorter time period. Our study demonstrates that although the magnitude of responses differed greatly among ecosystems, the direction of the responses was very similar across different ecosystems. Interactions between plant productivity and below-ground biogeochemical cycling need to be taken into account to predict ecosystem responses to environmental change.

scholarly journals Responses of two nonlinear microbial models to warming and increased carbon input

2016 ◽  
Vol 13 (4) ◽  
pp. 887-902 ◽  
Author(s):  
Y. P. Wang ◽  
J. Jiang ◽  
B. Chen-Charpentier ◽  
F. B. Agusto ◽  
A. Hastings ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Carbon Storage ◽  
Numerical Solutions ◽  
Nonlinear Models ◽  
Kinetics Model ◽  
Future Climate Change ◽  
Co2 Efflux ◽  
Soil Warming ◽  
Carbon Decomposition

Abstract. A number of nonlinear microbial models of soil carbon decomposition have been developed. Some of them have been applied globally but have yet to be shown to realistically represent soil carbon dynamics in the field. A thorough analysis of their key differences is needed to inform future model developments. Here we compare two nonlinear microbial models of soil carbon decomposition: one based on reverse Michaelis–Menten kinetics (model A) and the other on regular Michaelis–Menten kinetics (model B). Using analytic approximations and numerical solutions, we find that the oscillatory responses of carbon pools to a small perturbation in their initial pool sizes dampen faster in model A than in model B. Soil warming always decreases carbon storage in model A, but in model B it predominantly decreases carbon storage in cool regions and increases carbon storage in warm regions. For both models, the CO2 efflux from soil carbon decomposition reaches a maximum value some time after increased carbon input (as in priming experiments). This maximum CO2 efflux (Fmax) decreases with an increase in soil temperature in both models. However, the sensitivity of Fmax to the increased amount of carbon input increases with soil temperature in model A but decreases monotonically with an increase in soil temperature in model B. These differences in the responses to soil warming and carbon input between the two nonlinear models can be used to discern which model is more realistic when compared to results from field or laboratory experiments. These insights will contribute to an improved understanding of the significance of soil microbial processes in soil carbon responses to future climate change.

Soil CO2 evolution and root respiration in 11 year-old loblolly pine (Pinus taeda) plantations as affected by moisture and nutrient availability

2000 ◽  
Vol 30 (3) ◽  
pp. 347-359 ◽  
Author(s):  
C A Maier ◽  
L W Kress
Keyword(s):  
Carbon Source ◽  
Soil Temperature ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Forest Floor ◽  
Root Respiration ◽  
Carbon Sink ◽  
Annual Carbon ◽  
The Difference ◽  
Pinus Taeda L

We measured soil CO2 evolution rates with (Sff) and without (Sms) the forest floor litter and root respiration monthly in 11-year-old loblolly pine (Pinus taeda L.) plantations during the fourth year of fertilization and irrigation treatments. Values of Sff ranged from less than 1 µmol·m-2·s-1 during the winter to greater than 5 µmol·m-2·s-1 in late spring. Average Sff was significantly greater in unfertilized relative to the fertilized stands; however, there was no difference in average Sms among treatments. Soil temperature and the mass of the forest floor (litter) explained most of the difference in Sff among treatments. Soil temperature and volumetric water content accounted for 70% of the seasonal variation in Sff. Annual carbon efflux from the soil averaged 14.1 Mg·ha-1 per year for all treatments. Most of the evolved carbon was derived from root respiration (50-73%). Net ecosystem productivity was -1.1 and 6.9 Mg C·ha-1 per year for the unfertilized and fertilized stands, respectively. At age 11, the unfertilized stands were functioning as a net carbon source, while fertilized stands were a strong carbon sink. It was concluded that fertilization could decrease the time for a young pine plantation to change from a carbon source to a carbon sink.

scholarly journals Variability of aboveground litter inputs alters soil physicochemical and biological processes: a meta-analysis of litterfall-manipulation experiments

2013 ◽  
Vol 10 (3) ◽  
pp. 5245-5272 ◽  
Author(s):  
S. Xu ◽  
L. Liu ◽  
E. J. Sayer
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Inorganic Nitrogen ◽  
Meta Analysis ◽  
Mineral Soil ◽  
Total Carbon ◽  
Litter Addition ◽  
Subtropical Forests ◽  
Aboveground Litter ◽  
Soil Temperature And Moisture

Abstract. Global change has been shown to greatly alter the amount of aboveground litter inputs to soil, which could cause substantial cascading effects on belowground biogeochemical cyling. Although having been studied extensively, there is uncertainty about how changes in aboveground litter inputs affect soil carbon and nutrient turnover and transformation. Here, we conducted a comprehensive compilation of 68 studies on litter addition or removal experiments, and used meta-analysis to assess the responses of soil physicochemical properties and carbon and nutrient cycling under changed aboveground litter inputs. Our results suggested that litter addition or removal could significantly alter soil temperature and moisture, but not soil pH. Litter inputs were more crucial in buffering soil temperature and moisture fluctuations in grassland than in forest. Soil respiration, soil microbial biomass carbon and total carbon in the mineral soil increased with increasing litter inputs, suggesting that soil acted as a~net carbon sink although carbon loss and transformation increased with increasing litter inputs. Total nitrogen and the C : N ratio in the mineral soil increased with increased litter inputs. However, there was no correlation between litter inputs and extractable inorganic nitrogen in the mineral soil. Compared to other ecosystems, tropical and subtropical forests are more sensitive to variation in litter inputs. Increased or decreased litter inputs altered the turnover and accumulation of soil carbon and nutrient in tropical and subtropical forests more substantially over a shorter time period compared to other ecosystems. Overall, our study suggested that, although the magnitude of responses differed greatly among ecosystems, increased litter inputs generally accelerated the decomposition and accumulation of carbon and nutrients in soil, and decreased litter inputs reduced them.

scholarly journals Responses of two nonlinear microbial models to warming or increased carbon input

2015 ◽  
Vol 12 (17) ◽  
pp. 14647-14692 ◽  
Author(s):  
Y. P. Wang ◽  
J. Jiang ◽  
B. Chen-Charpentier ◽  
F. B. Agusto ◽  
A. Hastings ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Nonlinear Models ◽  
Analytic Solutions ◽  
Kinetics Model ◽  
Future Climate Change ◽  
Co2 Efflux ◽  
Soil Warming ◽  
Soil Microbial ◽  
Carbon Decomposition

Abstract. A number of nonlinear microbial models of soil carbon decomposition have been developed. Some of them have been applied globally but have yet to be shown to realistically represent soil carbon dynamics in the field. Therefore a thorough analysis of their key differences will be very useful for the future development of these models. Here we compare two nonlinear microbial models of soil carbon decomposition: one is based on reverse Michaelis-Menten kinetics (model A) and the other on regular Michaelis-Menten kinetics (model B). Using a combination of analytic solutions and numerical simulations, we find that the oscillatory responses of carbon pools model A to a small perturbation in the initial pool sizes have a higher frequency and damps faster than model B. In response to soil warming, soil carbon always decreases in model A; but likely decreases in cool regions and increases in warm regions in model B. Maximum CO2 efflux from soil carbon decomposition (Fmax) after an increased carbon addition decreases with an increase in soil temperature in both models, and the sensitivity of Fmax to the amount of carbon input increases with soil temperature in model A; but decreases monotonically with an increase in soil temperature in model B. These differences in the responses to soil warming and carbon input between the two nonlinear models can be used to differentiate which model is more realistic with field or laboratory experiments. This will lead to a better understanding of the significance of soil microbial processes in the responses of soil carbon to future climate change at regional or global scales.

Wildfire alters belowground and surface wood decomposition on two national forests in Montana, USA

2019 ◽  
Vol 28 (6) ◽  
pp. 456 ◽  
Author(s):  
Deborah S. Page-Dumroese ◽  
Martin F. Jurgensen ◽  
Chris A. Miller ◽  
James B. Pickens ◽  
Joanne M. Tirocke
Keyword(s):  
Mass Loss ◽  
Loblolly Pine ◽  
Populus Tremuloides ◽  
Mineral Soil ◽  
Soil Surface ◽  
National Forest ◽  
Ecosystem Responses ◽  
Surface And Interface ◽  
Pinus Taeda L ◽  
Bitterroot National Forest

Wildfires can drastically alter belowground processes such as organic matter (OM) decomposition. We used wood stakes of two different tree species, trembling aspen (Populus tremuloides Michx.) and loblolly pine (Pinus taeda L.), placed at three soil locations (soil surface, forest floor–mineral soil interface, mineral soil), as an index of the long-term (5-year) effects of wildfire on OM decomposition in two forest stands after high-severity wildfire and in an unburned control. Wood stake mass loss was generally higher for aspen, especially in the mineral soil of burned plots, than in control plots after 5 years. Soil surface and interface (unburned stands only) stakes showed few significant differences for either species on the Bitterroot National Forest. On the Gallatin National Forest, both pine and aspen stakes had significantly greater mass loss at the interface (unburned stand) at the end of 5 years, and also decayed significantly faster at the 10–20-cm depth in the wildfire area. Using wood stakes as an index of soil microsite properties in burned and unburned plots, we show that fire increased both OM decomposition and mineral soil microsite variability. These results strengthen our understanding of soil-surface and belowground ecosystem responses to wildfire.

The effects of vegetation control and fertilization on net nutrient release from decomposing loblolly pine needles

2003 ◽  
Vol 33 (12) ◽  
pp. 2491-2502 ◽  
Author(s):  
Nevzat Gurlevik ◽  
Daniel L Kelting ◽  
H Lee Allen
Keyword(s):  
Mass Loss ◽  
Loblolly Pine ◽  
Forest Floor ◽  
Mineral Soil ◽  
Nutrient Release ◽  
Phosphorus Fertilization ◽  
Available N ◽  
Vegetation Control ◽  
Needle Litter ◽  
Pinus Taeda L

This study examined the effects of vegetation control and nitrogen + phosphorus fertilization on decomposition and nutrient release dynamics of loblolly pine (Pinus taeda L.) needle litter. Needle litter was placed in litterbags and left to decompose on the forest floor, and changes in mass loss and nutrient (N, P, K, Ca, Mg, S, Mn, Zn, B, Cu) concentrations and contents were observed at 2- to 6-month intervals for 32 months. Fertilization had no effect on mass loss, while vegetation control resulted in a warmer and drier forest floor and led to reduced mass loss (k = 0.39 and 0.28 year–1 for fertilization and vegetation control, respectively). Concentrations of N, P, Ca, S, Zn, and Cu in the decomposing litter increased two- to three-fold over the 32 months, while concentrations of K, Mg, Mn, and B declined, increased, or did not change depending on time and treatment. Based on the release dynamics, the nutrient mobility series was as follows: Cu [Formula: see text] N [Formula: see text] S < P < Zn [Formula: see text] Ca < K [Formula: see text] Mn < Mg [Formula: see text] B. Fertilization had no effect on release dynamics; however, vegetation control reduced release of N, P, S, and Zn, and increased release of B. The mineral soil may be the main source of plant available N and P in midrotation southern pine stands based on the slow release of these elements from decomposing needle litter.

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